A rock fracture study of the Mactaquac Dam site, New Brunswick, Canada

Abstract

This report examines the bedding and joint patterns of a 4 km2 field area around the Mactaquac Dam in New Brunswick, Canada. Due to a chemical process in the concrete, known as alkali-aggregate reaction, the Mactaquac dam is in a gradually deteriorating condition and will need to be rebuilt (or repaired) in the next twenty-five years. The data presented in this report will assist with the future of the dam. During the summer and fall of 2004, data was collected based of dip and dip direction measurements in the Mactaquac Dam field area. The field data and previous data from 1966 were used with a computer program to find an average measurement of the bedding and four joint sets. Using a method developed by Hoek and Bray (1981), a wedge failure analysis was undertaken for each of the ten intersections in order to determine a favorable orientation of construction of a new powerhouse. Based upon the data from this report, the most favorable orientation for a new powerhouse strikes 040° and 130°, which is the orientation of the current powerhouse. When more firm plans are presented for the location of the new dam and/or powerhouse, this data should be reexamined to take note of possible confining directions.